Vinceti has no doubt that da Vinci was commissioned to paint a portrait of Gherardini, but he is not certain whether the painting that now hangs in the Louvre in Paris is of her, or just contains some of her features.

For starters, he says, that famous smile is not Gherardini's. Analysis of the "Mona Lisa" shows, he says, that "when Leonardo began painting the model in front of him, he did not draw that metaphysical, ironic, poignant, elusive smile, but rather he painted a person who was dark and depressed."

The smile, he believes, was added later, and probably belongs to da Vinci's longtime assistant (and rumored lover) Gian Giacomo Caprotti, whose distinct features appear in other works by da Vinci. Other art historians say the "Mona Lisa" is a surreptitious self-portrait.

There is something eccentric, or slightly mad, about Vinceti. A former producer for RAI, the Italian state broadcaster, he speaks in the language of veteran television producers the world over -- emphatic, direct and full of expletives. In the past, he's produced documentaries about his attempts to solve old art mysteries and plans to do the same with his current project on the "Mona Lisa." His high-profile efforts have been criticized by academics, but Vinceti brushes them off with a dismissive snort.

Part of his motivation in this current project is a personal identification with da Vinci, who, Vinceti says, "never went to university, didn't learn Greek or Latin, and was not considered learned."

It will be several months before DNA tests can be conducted and the reconstruction of Gherardini's face can be completed. And regardless of the results, Vinceti concedes that da Vinci is beyond comprehension: "This is the magic of a great genius who eludes classification, around whom remains a fog of mystery. I am under no illusion that we will be able to solve the mystery of the 'Mona Lisa.'